Dynamic image correction method and dynamic image correction circuit for display device

ABSTRACT

A display device which displays a multilevel gradation image by dividing a frame into a plurality of subfields in respect of time and by allowing the subfields corresponding to the luminance levels of the input image signals to emit light, comprising a motion vector detection unit  10  which detects the motion vector which expresses the motion of a block from one frame to the next, a high speed dynamic image correction unit  14  and a law speed dynamic image correction unit  16  which correct the input image signal by dynamic image correcting means which are suitable for the respective cases when the value of the detected motion vector is larger than a preset value S and when it is smaller than the preset value S and output the corrected input image signal, and a switching unit  18  which elects either the output signal of the high speed dynamic image correction unit  14  or the output signal of the law speed dynamic image correction unit  16  to output the selected signal to the display in accordance with whether or not the value of the detected motion vector is larger than the preset value S. As a result, both the high speed dynamic image part and the low speed dynamic image part of the image can be optimally corrected.

FIELD OF THE INVENTION

The present invention relates to a dynamic image correction method anddynamic image correction circuit of display device, wherein one frame isdivided into a plurality of subfields (or subframes) on time-sharingbasis and the subfields are made to emit light according to luminancelevels of input signals for producing multi-gradation image.

BACKGROUND ART

Display devices incorporating PDP (Plasma Display Panel) and LCD (LiquidCrystal Display) are now attracting the attention of those who concernedas thin and lightweight display device. This drive method of the PDP isentirely different from that of conventional CRT in that the PDP isdirectly driven by input of digitized video signal. Thus, the luminanceand gradation of the light emitted from panel surface are dependent onthe number of bits of signal to be processed.

The PDP can be divided into two types, namely, AC-type and DC-typesdiffering in basic characteristic. As for the AC-type PDP, sufficientcharacteristics can be obtained as to luminance and service life, whileavailability of only up to 64 gradations has been reported on trialmanufacture basis, but a method for enabling 256 gradations by addressdisplay separation method in the future has already been proposed.

Drive sequence and drive waveform of the PDP to be used in this method,for example in the case of 8 bits and 256 gradations, are as shown inFIGS. 1(a) and (b) respectively.

In FIG. 1(a), one frame comprises 8 subfields SF1, SF2, SF3, SF4, SF5,SF6, SF7 and SF8 having luminance ratios of 1, 2, 4, 8, 16, 32, 64, 128,and display of 256 gradations is available by Combining the luminancesof 8 images.

In FIG. 1(b), each subfield comprises an address period for writing thedata for 1 image and a sustain period for determining the luminancelevel of the subfield. During the address period, initial wall charge isformed simultaneously for each of the pixels of all the images, and thensustain pulse is given to all the images for display. The brightness ofthe subfield is proportional to the number of the sustain pulse and setto a predetermined luminance. The 256-gradation display is madeavailable in this way.

When displaying a dynamic image by using an address display separationtype display device as is described previously, input video signal(original signal) is a discrete signal, which is sampled for each frame(or field), thereby giving rise to a problem such as degradation ofpicture quality resulting from the visual disagreement in the directionof the movement of the dynamic image and the presence of the level notin accordance with the original signal. The dynamic image correctionaccording to the prior art has been made by applying only onepredetermined dynamic image correction method on the basis of the inputvideo signal, regardless of the rate of the movement of block during oneframe or during a plurality of frames. Here, one block means an area ofimage formed with one or a plurality of picture elements, e.g., 2×2picture elements.

According to the case of the prior art described above, however, thedynamic image is corrected by using only one same dynamic imagecorrection method regardless of rapid moving part of dynamic image(hereinafter referred to as “rapid moving dynamic image part”) and slowmoving part of dynamic image (hereinafter referred to as “slow movingdynamic image part”), thereby causing a problem such that, when thedynamic image correction method is adapted for the rapid moving dynamicimage part, correction for the slow moving dynamic image part becomesinsufficient and vice versa.

The present invention, devised, in consideration of the problem of theprior art, for the display device having one frame divided into aplurality of subfields which emit light according to luminance level ofinput video signal for displaying multi-gradation image, is designed toprovide a dynamic image correction method and a dynamic image correctioncircuit capable of effecting optimum dynamic image correction for boththe rapid moving dynamic image part and the slow moving dynamic imagepart.

DISCLOSURE OF THE INVENTION

In the dynamic image correction method according to the presentinvention, for display device wherein one frame is divided into aplurality of subfields which emit light according to luminance level ofinput video signal for the display of multi-gradation image, the movingvector of the block during one frame or the blocks during a plurality offrames is or are detected, and, depending on whether the value ofdetected moving vector is larger than the preset value S or not, eithera signal obtained by correcting input video signal by the rapid movingdynamic image correction means or a signal obtained by correcting inputvideo signal by the slow moving dynamic image correction means isselectively output to the display device.

When the value of the moving vector detected on the basis of input videosignal is larger than the preset value S, the input video signal iscorrected by the rapid moving dynamic image correction means for outputto the display device, while when the value of the detected movingvector is smaller than the preset value S, the input video signal iscorrected by the slow moving dynamic image correction means for outputto the display device, whereby an optimum dynamic image correction canbe accomplished for both the rapid moving dynamic image part and slowmoving dynamic image part to be displayed on the display device.

Further, according to the dynamic image correction method of the presentinvention, the rapid moving dynamic image correction means not onlyselects the light emitted from corresponding subfields among n number ofsubfields, SFn, SF(n−1), . . . SF1, which constitute one frame,according to the luminance level of input video signal but also correctsthe display positions of the n number of subfields SFn˜SF1 in each frameof input video signal depending on the value of detected moving vector,while the slow moving dynamic image correction means selects the lightemitted from the subfields SF(n−1), . . . SF1 and SF1 a, SF1 a beingadjacent to SF1 and having a luminance ratio equivalent to that of SF1,which constitute one frame, only when the luminance levels of inputvideo signal has varied from 2^((n−1))−1 to 2^((n−1)), but selects thelight emitted from the corresponding subfields among n number ofsubfields, SFn˜SF1 not including the subfield SF1 a with respect to theluminance levels other than those described previously. Therefore, whenthe value of detected moving vector is larger than the preset value S,the display positions of the subfields SFn˜SF1 can be made to match withthe visual path of the eye of a person watching the dynamic image. Onthe other hand, when the value of detected moving vector is smaller thanthe preset value S, the light emitted from the subfields, SF(n−1)˜SF1and SF1 a (e.g., SF3, SF2, SF1 and SF1 a) is selected by the slow movingdynamic image correction means with respect to luminance level at2^((n−1)) (e.g., 8 when n=4) resulting when a luminance level has variedslightly from 2^((n−1))−1 (e.g., 7) to a luminance level at2^((n−1))(e.g., 8), thereby eliminating large variation of luminance.

The dynamic image correction circuit of present invention, incorporatedinto the display device wherein one frame is divided into a plurality ofsubfields on time-sharing basis for emitting light from the subfieldsaccording to luminance level of input video signal to displaymulti-gradation image, comprises a moving vector detector for detectingthe moving vector of the block during one frame or moving vector of theblock during a plurality of frames, a rapid moving dynamic imagecorrector for correcting for output an input video signal by using aproper dynamic image correction means when the value of the movingvector detected by the moving vector detector is larger than presetvalue S, a slow moving dynamic image corrector for correcting for outputan input video signal by using a proper dynamic image correction meansand a discriminating selector for discriminating an output signal fromthe rapid moving dynamic image corrector from an output signal from theslow moving dynamic image corrector for output to the display devicedepending on whether the value of the moving vector detected by themoving vector detector is larger or smaller than the preset value S. Thediscriminating selector outputs the input video signal corrected by therapid moving dynamic image corrector to the display device when thevalue of detected moving vector is larger than the preset value S andoutputs the input video signal corrected by the slow moving dynamicimage corrector to the display device when the value of detected movingvector is smaller than the preset value S, so that an optimum dynamicimage correction can be accomplished for both the rapid moving dynamicimage part and the slow moving dynamic image part to be displayed on thedisplay device.

The dynamic image correction circuit according to the present inventionis designed so that the rapid moving dynamic image corrector not onlyselects the light emitted from corresponding subfields among n number ofsubfields SFn˜SF1 constituting one frame and having luminance ratios2^((n−1)) through 2^(0(=n−n)) according to the luminance level of theinput video signal but also corrects display positions of n number ofsubfields SFn˜SF1 for each frame of input video signal depending on thevalue of moving vector detected by the moving vector detector, while theslow moving dynamic image corrector selects the light emitted from thesubfields, SF(n−1), . . . SF1, SF1 a, constituting one frame and havingluminance ratios 2^((n−1)), 2^((n−2)), . . . 2^(0(=n−n)), only when theluminance level of input video signal has varied from 2^((n−1))−1 to2^((n−1)) and also selects the light emitted from correspondingsubfields among n number of subfields, SFn˜SF1, not including subfieldSF1 a, as to the luminance level other than those prescribed previously.

Therefore, when the value of detected moving vector is larger than thepreset value S, the display positions of the subfields, SFn˜SF1 can bemade to match with the visual path of the eye of a person watching thedynamic image by using the rapid moving dynamic image corrector. On theother hand, when the value of detected moving vector is smaller than thepreset value S, the light emitted from the subfields, SF(n−1)˜SF1 andSF1 a (e.g., SF3, SF2, SF1 and SF1 a) is selected by the slow movingdynamic image corrector with respect to the luminance level at 2^((n−1))resulting when the luminance level has slightly varied from a luminancelevel at 2^((n−1))−1 (e.g., 7 when n=4) to 2^((n−1)) (e.g., 8), therebyeliminating large variation of luminance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the address display separation type drive method,wherein (a) is a diagram illustrating the drive sequence for256-gradation image, while (b) is a diagram illustrating drive waveform.

FIG. 2 shows the dynamic image correction circuit for practicing thedynamic image correction method for display device as an embodiment ofthe invention.

FIG. 3 is a diagram illustrating the drive sequence of the addressdisplay separation type drive method when n=4 is given for conveniencein illustrating the dynamic image correcting function of the slow movingdynamic image corrector shown in FIG. 2.

FIG. 4 schematically illustrates the dynamic image Correcting functionof the rapid moving dynamic image corrector shown in FIG. 2.

FIG. 5 shows a comparative embodiment to that shown FIG. 4 andschematically illustrates a case where rapid moving dynamic imagecorrection is not employed.

FIG. 6 schematically illustrates the dynamic image Correcting functionof the slow moving dynamic image corrector shown in FIG. 2.

FIG. 7 shows a comparative embodiment to that shown in FIG. 6, wherein(a) illustrates the drive sequence of the subfield method applied to acase of 16-gradation display, while (b) schematically illustrates a casewhere slow moving dynamic image correction is not applied.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail referring toaccompanying drawings.

FIG. 2 shows an embodiment of the dynamic image correction circuit forcarrying out the dynamic image correction method for the display deviceaccording to the present invention.

In FIG. 2, reference numeral 10 denotes the moving vector detector,which detects and outputs the moving vector (direction and amount ofmovement) of the block (e.g., 2×2 picture elements) during one frame orthe blocks during a plurality of frames on the basis of the video signalinput to input terminal 12. For instance, on the bases of the videosignals of the present frame and preceding frame, the moving vector ofthe block to be corrected for the image of the present frame of the PDPis detected and output by the moving vector detector.

Reference numeral 14 denotes the rapid moving dynamic image corrector,which corrects the video signal input to the input terminal 12 by properdynamic image correction means and outputs the corrected video signal,when the value of the moving vector detected by the moving vectordetector 10 is larger (e.g., equal to or larger than S) than the presetvalue S (e.g., 2 dots/frame).

Reference numeral 16 denotes the slow moving dynamic image corrector,which corrects the video signal input to the input terminal 12 by properdynamic image correction means and outputs the corrected video signal,when the value of the moving vector detected by the moving vectordetector 10 is smaller than the preset value S (e.g., S or less).

Reference numeral 18 denotes the discriminating selector, whichselectively outputs the signal output from the rapid moving dynamicimage corrector 14 or the signal output from the slow moving dynamicimage corrector 16 to output terminal 20, depending on whether the valueof the moving vector detected by the moving vector detector 10 is largeror smaller than the preset value S.

The rapid moving dynamic image corrector 14 has a construction, forexample, substantially the same as that of corresponding rapid movingdynamic image corrector for the dynamic image correction method and thedynamic image corrector according to (Japanese Patent ApplicationPublication No. H7-317508(317508/1995)), the application therefor havingalready been filed by the present applicant. That is, the rapid movingdynamic image corrector 14, comprising a data conversion circuit forconverting input n-bit video signal into display data of subfieldsSFn˜SF1 and a ROM (read-only memory) for outputting the datarepresenting the corrected display positions of the subfields SFn˜SF1with address represented by the detected moving vector, not only selectsthe light emitted from the corresponding subfields among the n number ofsubfields SFn˜SF1 according to the luminance level of video signal inputto the input terminal 12 but also outputs the signal corrected as to thedisplay positions of subfields SFn˜SF1 of each frame of input videosignal according to the value of the moving vector detected by themoving vector detector 10.

The slow moving dynamic image corrector 16 has a construction, forexample, substantially the same as that of the corresponding slow movingdynamic image corrector incorporated into the display device drivemethod according to Japanese Patent Application Publication No.H7-108191(108191/1995) which has been filed by the present inventor.That is, the slow moving dynamic image corrector 16 is designed toselect the light emitted from n number of subfields, SF(n−1), SF(n−2), .. . SF1 and adjacent SF1 a, composing one frame and having luminanceratios 2^((n−1)), 2^((n−2)), . . . 2^(0(=n−n)), only when the luminancelevel of the video signal, which has been input to the terminal 12, hasvaried from 2^((n−1))−1 to 2^((n−1)), and also selects the light emittedfrom the corresponding subfields among n number of subfields, SFn˜SF1,not including the subfield SF1 a, with respect to the luminance levelother than that described previously.

Next, the functions of the components shown in FIG. 2 will be describedreferring to FIGS. 3 through 7.

(1) First, referring to FIGS. 4 and 5, the corrective function for therapid moving dynamic image, when the value of the moving vector detectedby the moving vector detector 10 is larger than the present value S(e.g., 2 dots/frame), will be explained.

For convenience of explanation, as shown in FIG. 7(a), assume that oneframe is composed of 4 subfields (n=4) SF4, SF3, SF2 and SF1 withluminance ratios of 2³, 2², 2¹ and 2⁰, and the block of dynamic imagerelating to input video signal with luminance level 15 is to move in apredetermined direction at a rate of 5 dots (or 5 picture elements) perframe. Since the value (5 dots/frame) of the moving vector detected bythe moving vector detector 10 is larger than the preset value S (e.g., 2dots/frame), the signal output from the rapid moving dynamic imagecorrector 14 through the discriminating selector 18 is delivered to thedisplay device (e.g., PDP) through the output terminal 20.

(2) As shown in FIG. 4, the signal output from the rapid moving dynamicimage corrector 14 not only makes all the subfields SF4˜SF1 emit lightbut also generates a signal corrected so that the display positions ofsubfields SF4˜SF1 of each frame come within the range between solidlines a and b, corresponding to the detected moving vector (5dots/frame). That is, the signal is corrected for moving subfield SF4 by0 dot (i.e., remains at the original position) subfield SF3 by 2 dots,subfields SF2 and SF1 by 3 dots and 4 dots respectively.

Therefore, the maximum deviation zm can be reduced to less than half themaximum deviation ZM (FIG. 5) where display position is not corrected,thereby preventing vagueness in the case of monochrome display and colordivergence in the case of color display.

Further, in FIG. 4, the diagonal solid lines a and b represent the pathsalong which the block of dynamic image moving at a rate of 5 dots/frameis followed by the eye of a viewer, while the diagonal dotted linesrepresent the paths along which the block of dynamic image moving at arate of 8 dots/frame is followed by the eye of a viewer. Further, FIG. 5shows a comparative example, in which the dynamic image correctionmethod is not employed (i.e., the case where subfield display positioncorrection is not applied).

(3) Next, referring to FIGS. 6 and 7, explanation will be made as to thefunction in the case where the value of moving vector detected by themoving vector detector 10 is smaller than the preset value S (e.g., 2dots/frame).

For convenience of explanation, assume that one frame is composed of 4subfields (n=4) SF4, SF3, SF2, SF1 with luminance ratios of 2³, 2², 2¹,2⁰ and an adjacent subfield SF1 awith luminance ratio of 2⁰.

In this case, the Value of moving vector detected by the moving vectordetector 10 is smaller than the preset value S, so that the signaloutput from the slow moving dynamic image corrector 16 through thediscriminating selector 18 is delivered to display device (e.g., PDP)through the output terminal 20.

(3a) First, explanation will be made as to the effect of the inventionin the case where luminance level varies from 7 to 8 as the result oferror diffusion processing or the like.

The signal output from the slow moving dynamic image corrector 16 withluminance level 7 becomes a signal for bringing about the emission oflight by the subfields SF3, SF2 and SF1 as illustrated by the left sideof the change point in FIG. 6, while the signal, with luminance level 8that varied from luminance level 7, becomes a signal for causing theemission of light by subfields SF3, SF2, SF1 and SF1 a as illustrated bythe right side from the change point in FIG. 6.

Therefore, at the point where luminance level varies from 7 to 8, valueof bit varies from 01110 to 01111 and the emission of light will notcontinue, so that there will be no substantial variation of luminancesuch as that causing disagreement with the variation of original signal,thereby preventing the degradation of picture quality.

In contrast, as shown in FIG. 7(a), when one frame is composed of only 4subfields SF4˜SF1 without adding subfield SF1 a, at the point at whichluminance level varies from 7 to 8, as shown in FIG. 7(b), the value ofbit varies from 0111 to 1000 to continue the emission of light, and theluminance level at the change point becomes about twice the luminancelevel 7 or 8, thereby causing a problem such as the rod disagreementwith the variation of original signal.

(3b) Next, explanation will be made as to the case other than the casedescribed in (3a). In this case, the signal output from the slow movingdynamic image corrector 16 will become a signal resulting from selectingthe emission of light by the subfields corresponding to luminance levelamong the 4 subfields not including the subfield SF1 a as describedpreviously in (3). For instance, when the luminance level of input videosignal is 8, signal is generated by selecting the emission of light fromsubfield SF4; when the luminance level is 7, signal generated byselecting the emission of light from subfields SF3, SF2 and SF1; whenthe luminance level is 3, signal generated by selecting the emission oflight from subfields SF2 and SF1; when the luminance level is 8resulting from variation from 7, signal generated by selecting theemission of light from subfield SF4, respectively.

In the embodiment described above, the rapid moving dynamic imagecorrector is explained with reference to the case where one frame iscomposed of 4 subfields SF4˜SF1, whereas the slow moving dynamic imagecorrector is explained with reference to the case where one frame iscomposed of 4 subfields SF4˜SF1 and a subfield SF1 a adjacent to thesubfield SF1, 5 subfields in total (i.e., 5 bits), but the presentinvention is not limited to this. For instance, the rapid moving dynamicimage corrector is applicable to the case where one frame is composed ofn number (n is any integer not less than 2) of subfields SFn˜SF1, whilethe slow moving dynamic image corrector is applicable to the case whereone frame is composed of n+1 number of subfields, i.e., n number ofsubfields SFn˜SF1 plus one subfield SF1 a in total, (case where theimage is of gradation of 2^(n)). Further, the latter can also be appliedto the case where the subfield SF1 a is omitted.

For instance, the slow moving dynamic image corrector is also applicableto the case where one frame is composed of 6 subfields in total (i.e., 6bits), that is, 5 subfields (n=5), SF5˜SF1, and 1 subfield SF1 a, whichis adjacent to SF1, (a case where the image to be displayed is of 32gradations). In this case, the signal output from the slow movingdynamic image corrector 16, described previously in (3), becomes asignal to induce the emission of light from the subfields SF4, SF3, SF2,SF1 and SF1 a only when the luminance level has varied to 16 from 15.Therefore, at the point at which the luminance level varies from 15 to16, bit value varies from 011110 to 01111, and the emission of lightwill not continue, so that there is no substantial variation ofluminance level thereby preventing degradation of picture quality.

In the above embodiment, the rapid moving dynamic image corrector isdesigned not only to select the emission of light from correspondingsubfields among n number of subfields SFn˜SF1 according to the luminancelevel of input video signal but also corrects the display positions ofthe n number of subfields of each frame of input video signal accordingto the value of the moving vector, but the present invention is notlimited to this embodiment, and thus it is sufficient for the rapidmoving dynamic image corrector to be any one which is capable ofcorrecting input video signal for output by using proper correctionmeans when the value of the moving vector detected by the moving vectordetector is larger than the preset value S.

In the above embodiment, the slow moving dynamic image corrector isdesigned to select the light emitted from subfields SF(n−1), . . . SF1and SF1 a only when the luminance level of input video signal has variedfrom 2^((n−1))−1 to 2^((n−1)), and select the light emitted fromcorresponding subfields among n number of subfields SFn˜SF1 notincluding subfield SF1 a with respect to the luminance level other thanthat described previously, but the present invention is not limited tothis embodiment, and thus it is sufficient for the slow moving dynamicimage corrector to be any one which is capable of correcting for outputthe video signal by using proper dynamic image correction means when thevalue of the moving vector detected by the moving vector detector issmaller than the preset value S.

In the above embodiment, an explanation is made as to the case ofdisplay device using the PDP, but the present invention is not limitedthis, that is, the present invention is also applicable to the digitaldisplay device (e.g., display device using LCD).

INDUSTRIAL AVAILABILITY

As described in the foregoing, the present invention is designed toprovide an optimum dynamic image correction for both the rapid movingpart and slow moving part of dynamic image when applied to a displaydevice (e.g., display devices using PDP or LCD), wherein one frame isdivided into a plurality of subfields on time-sharing basis, and theimage of multigradation is produced by having subfields emit lightaccording to the luminance level of input video signal.

What is claimed is:
 1. A dynamic image correction method for displaydevice, the display device having one frame divided into a plurality ofsubfields for producing multigradation image by having the subfieldsemit light according to the luminance level of input video signal,wherein the moving vector of a block during one frame or during aplurality of frames is detected on the basis of the input video signal,and the signal obtained by correcting the input video signal by eitherthe rapid moving dynamic image correction means or the slow movingdynamic image correction means is selectively output to the displaydevice depending on whether the value of the detected moving vector islarger or smaller than the preset value S.
 2. A dynamic image correctionmethod for display device according to claim 1, wherein the rapid movingdynamic image correction means not only selects the light emitted fromcorresponding subfields among n number of subfields SFn˜SF1 according tothe luminance level of input video signal, the n number of subfieldsconstituting one frame and having luminance ratios of 2^((n−1)) (n=anyinteger not less than 2) through 2^(0(=n−n)), but also corrects displaypositions of the n number of subfields SFn˜SF1, which constitute eachframe of the input video signal, depending on the value of the detectedmoving vector, while the slow moving dynamic image correction meansselects the light emitted from subfields SF(n−1)˜SF1 and SF1 a only whenthe luminance level of input video signal has varied from 2^((n−l))−1 to2^((n−1)), the n number of subfields SFn˜SF1 and SF1 a, the SF1 a beingadjacent to SF1, constituting one frame and having Luminance ratios of2^((n−1)) through 2^(0(n−n)), and also selects the light emitted fromcorresponding subfields among n number of subfields SFn˜SF1 notincluding the subfield SF1 a with respect to the luminance levels otherthan those described above.
 3. A dynamic image correction circuit ofdisplay device, the display device having one frame divided into aplurality of subfields on time-sharing basis to produce multigradationimage by having corresponding subfields emit light according to theluminance level of input video signal, comprising a moving vectordetector for detecting the moving vector of a block during one frame orduring a plurality of frames according to the input video signal, arapid moving dynamic image corrector for correcting the input videosignal for output by using a proper dynamic image correction means whenthe detected value of moving vector is larger than preset value S, aslow moving dynamic image corrector for correcting the input videosignal by using a proper dynamic image correction means when thedetected value of moving vector is smaller than the preset value S and adiscriminating selector for selectively output the signal output fromthe rapid moving dynamic image corrector or the signal output from theslow moving dynamic image corrector depending on whether the value ofthe detected moving vector is larger or smaller than the preset value S.4. A dynamic image correction circuit for display device according toclaim 3, wherein the rapid moving dynamic image corrector not onlyselects the light emitted from corresponding subfields among n number ofsubfields SFn˜SF1 according to the luminance level of input videosignal, the n number of subfields SFn˜SF1 having luminance ratios of2^((n−1)) (n=any integer not less than 2) through 2^(0(=n−n)) andconstituting one frame, but also corrects the display position of the nnumber of subfields SFn˜SF1, which constitute each frame of the videosignal, depending on the value of detected moving vector, while the slowmoving dynamic image corrector selects the light emitted fromcorresponding subfields among n number of subfields SFn˜SF1 and subfieldSF1 a only when the luminance level of input video signal has variedfrom 2^((n−1))−1 to 2^((n−1)), the subfields SFn˜SF1 and subfield SF1 ahaving luminance ratios of 2^((n−1)) through 2^(0(=n−n)) andconstituting one frame, and also selects the light emitted fromcorresponding subfields among n number of subfields SFn˜SF1 notincluding subfield SF1 a with respect to the luminance levels other thanthose described above.